    \begin{tikzpicture}
    %------------------------------------------------------------------------------------
    %    图片2.6
        \node (E) at (0,0) {E}
		[level 1/.style={level distance=3em, sibling distance=5em},
		level 2/.style={level distance=3em, sibling distance=2.5em},
		level 3/.style={level distance=3em, sibling distance=2em}]
            child {node {E}
                child {node (2E) {E}}
                child {node {+}}
                child {node {T}
                    child {node {F}}
                }
            }
            child {node {-}}
            child {node {T}
                child {node {T}
                    child {node (3T) {T}}
                    child {node {/}}
                    child {node {F}}
                }
                child {node {*}}
                child {node (2F) {F}
                    child {node (3i) {i}}
                }
            };
        
\end{tikzpicture}